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【单选题】
哈勃定律反映了宇宙的整体膨胀而不是星系在不变的宇宙背景中的运动。如果宇宙在均匀膨胀，那么宇宙的年龄大约是()亿年。
A.
100
B.
140
C.
200
D.
50
参考答案：
参考解析：
刷刷题刷刷变学霸
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【单选题】How should one invest a sum of money in these days of inflation (通货膨胀) Left in a bank it will hardly keep its value, however high the interest rate is. Only a brave man, or a very rich one, dares to b...
A.
suggest human beings are controlled by a clock
B.
describe why clocks can rule the planet Earth
C.
tell readers what clocks look like
D.
compare clicks to human beings
【单选题】关于压缩空气起动的正确论述 。 I.起动空气应有足够压力和一定储量 II.起动空气必须在膨胀行程中进入气缸 III.四冲程柴油机起动最少有4个气缸 IV.二冲程进气延续角约为100°曲轴转角 V.达到起动转速后柴油机才能发火起动 VI.二冲程柴油机起动最少有六个气缸
A.
Ⅰ+Ⅱ+Ⅲ+Ⅳ
B.
Ⅰ+Ⅱ+Ⅳ+Ⅴ
C.
Ⅱ+Ⅲ+Ⅳ+Ⅴ
D.
Ⅱ+Ⅳ+Ⅴ+Ⅵ